161 
computing the actual breeding population, only paired and single ducks were 
considered as the resident breeding population. Further examination of Table LV 
will be made in this connection below. 
Table II presents the species composition of the duck breeding pair population 
in May 1953. Mallards composed 62 percent of the total, with gadwalls 10 percent, 
teal 8 percent, and American mergansers 8 percent, the only other important 
breeding species in the State. 
An attempt has been made this year to obtain a tentative figure for the total duck 
breeding pair population for the State in May (Table III). The techniques used have 
been outlined under ''Methods" above. Both mileage of streams flown and total miles 
of unsurveyed waterfowl habitat were taken off a 1" - 8 mile scale, base map of 
Wyoming with a map measurer. Perimeters were considered to represent the amount 
of duck habitat on lakes large enough to be shown on the map. It was assumed that the 
greater breeding density of large, downstream surveyed water areas would partially 
compensate for the myriad of marshes, ponds and small streams utilized by ducks in 
the mountains and foothills, but not shown on the base map and unknown to project 
personnel. In addition, mileage on a representative number of streams not surveyed 
were carried into the mountains farther than might ordinarily be warranted to include 
beaver ponds. In other cases mileage on unsurveyed streams was not measured for 
the entire portions on which ducks were known to nest. For instance, it would be 
unrealistic to credit the entire length of Smith's Fork (a tributary to the Bear River) 
with the same high nesting density as was found on the Bear River. 
As has been mentioned above, it became apparent in the May inventory that ducks 
observed in large groups were migrating and could not be included as part of the 
resident breeding population of the areas flown. Also, large numbers of paired diving 
ducks, evident in May, but absent in July, were not considered as belonging to the 
resident breeding population. An adjustment was made, then, to correct Table I. The 
figures shown in column 3 of Table III represent only the total paired and single ducks 
believed to have nested on the portions of the drainages surveyed. 
Species composition for the total State breeding pair population would not coincide 
(percentagewise) with Table II. The relative abundance of mallards, teal, mergansers 
and goldeneye would increase, whereas diving ducks, pintail, gadwall, baldpate and 
Shovelers would register a significant drop. 
Table I. - Total Number of Ducks Observed by Aerial Count on Major Drainages in 
: : Wyoming, May 1953 
Drainage Pairs Singles * Groups Total Ducks 
Green 797 387 596 2,964 
Snake 473 360 471 2,137 
Bear 605 332 528 2,402 
Salt 369 366 270 1, 740 
Wind 536 348 5,147 6,915 
Big Horn 422 332 —C 586 2,094 
Belle Fourche-Cheyenne 47 24 142 284 
North Platte 5,493 85 1,617 12,773 
Powder -Tongue 13 22 260 330 
Total 8,755 2,256 9,617 31,639 
* A single bird in May was considered as a mated pair. 
